This invention is related to the vapor phase hydrogenation of carbon tetrachloride to form chloroform and methylene chloride.
Various methods of dehalogenating saturated and unsaturated organic compounds are known. For example, U.S. Pat. No. 3,579,596, issued to Mullin et al. on May 18, 1971, is directed to the vapor phase dechlorination of carbon tetrachloride and/or chloroform in the presence of a platinum catalyst. The hydrodechlorination of carbon tetrachloride with hydrogen over peripherally deposited platinum on alumina is also discussed by Weiss et al. in Journal of Catalysis 22, 245-254 (1971). However, as discussed by Noelke and Rase in Ind. Eng. Chem. Prod. Res. Dev. 18, 325-328 (1979), such processes have been marked with poor selectivity, rapidly declining catalyst activity and short reactor operating cycles. Various treatments have been explored to improve activity and selectivity. These include pretreating catalysts with sulfur and hydrogen.
A need remains for a process for hydrogenating carbon tetrachloride to form chloroform and methylene chloride that is selective to the desired products, results in minimal by-product formation and shows minimal decline in catalyst activity.